Method of drying coal and the like



i so great,

Patented June 21, 1927.

UNITED STATES 1,632,829 PATENT OFFICE.

HANS FLEISSNER, OIF LEOBEN, AUSTRIA.

METHOD OF DRYING GOAL AND THE LIKE.

No Drawing. Application filed Januaryll, 1926, Serial No. 80,665, and. in Austria August 14, 1924.

This invention relates to an improved method of drying coal and the like.

Further it has been proposed to gradually heat the materials to be dried at firstwith a vapor-laden atmosphere but at a temperature below the vaporizing temperature of the moisture, and thereafter accelerating the drying operation, which is very slow at the beginning, by condensing the moisture of the air which is again returned and reheated during the circulation.

According to the present invention this drawback is avoided in that the colloidal character of the material is abolished as far as possible before the drying operation. This may be accomplished by some sort 0 coagulation of the colloids, if the coals are heated to a higher temperature and thereby care is taken, from the coal during this procedure. In carrying out the invention, first the coal is heated up to drying temperature inv the presence of steam or by the latter whereby care is to be taken, that the partial pressure of the steam above the fuel to be dried is that the water cannot escape from the coal during the heating. In order to attain this, it is only necessary to pass saturated steam of a suitable temperature over the coal, until the same has taken on the temperature required for the drying. Only after the coal has been subjected in this manner for some time to the necessary drying temperature, the water is allowed to escape from the coal by progressively reducing the steam-pressure, and now the coal is drying quickly. For this object air-is now passed over the coal, so that a progressive reduction of the steam-pressure takes placeand the coal is dried quite uniformly without fallin to pieces.

A suita le apparatus for carrying out the present invention is diagrammatically illusthat water does not escapepheres,

sure ranging from 3 trated by way of example in the accompanying drawing.

In the drawing, 1 indicates a closed drying chamber, provided with an inclined perforated bottom 2, the lower end of Which leads to a. discharge opening 8, which is adapted to be closed. The top end of the drying chamber terminates in a funnel 4, which can be closed. A pipe 5 for supplying saturated steam and a pipe 6 for hot air communicate with the interior of the chamber lunderneath the perforated bottom 2, and both pipes are furnished with closing members; A pipe 7 for discharging the vapors and gases is connected to the top of the drying chamber.

For carrying out the method, saturated steam is supplied for such a length of time, until the brown coal is heated to about 100 Celsius, without losing the moisturer At this temperature the brown coal loses its colloidal character. The steam and hot air are discharged through the pipe 7 and for ably separating the same underneath the perforated bottom.

After the material is completely dried, the

f same is discharged through the opening The temperature, steam pressure and tlme of action differs according to the moisturecontent and place of origin of the coal. For instance brown-coal from. the Alexander mine in Bohemia is heated for about three quarters of an hour at a pressure of 3 atmoscorresponding to about 130 centigrade and subsequently is dried for about 2 hours by reducing the partial steam pressure. The coal from the Koflacher mine in Austria contains a considerably greater quantity of water and calls for a pressure of about 15 atmospheres corresponding to about 197 centigrade and a steam treatment for about one hour, and subsequently has to be dried between 2 and 3 hours;

I claim 1. Method of drying coal andthe like consisting in first heating the coal for about one hour in the presence of steam of a presatmospheres correspondin to a temperature of about 130 centigra e to a temperature of about 235 centigrade thus preventing the escape of water from the coal, thereafter progressively reducing the pressure of the steam in order to start to 25 atmospheres corresponding a the drying, end continuing this reduction until the coal is dry.

ranging from 3 atmosgheres corresponding to a temperature of a out 130 centigrade to 25 atmospheres corresponding to a temperature of about 235 cent-igrade thus preventing the escape of water from the coal, thereafter progressively reducing the pressure of the steam inorder to start the drying, and continuing this reduction until the coal is dry.

In testimony whereof I aflix my signature.

VDR. HANS FLEISSNER.v 

